MXPA98006384A - Device for the evaporation of an active substance, liquid - Google Patents

Abstract

The invention relates to a device for evaporating an active, fluid substance (12). This device has a wick (7) which can be immersed in the active, fluid substance (12) and is proposed to distribute the active substance. When immersed one end of the wick protrudes from the active, fluid substance and is provided with a heating device (3) provided in the wick in the region of the protruding end. The device is characterized in that the shape of the wick is such that the active, fluid substance (12) can not substantially pass through the outer surface of the wick at least along the length thereof, which is immersed in the active substance, fluid, the active, fluid substance (12) can pass substantially through the wick in the region of its end surface (10) opposite the protruding end, and the evaporation of the active substance (12) can pass through the heating device region (3) at least when the wick is heated. Therefore, the active substance, fluid, rises uniformly in the mec

Description

DEVICE FOR THE EVAPORATION OF AN ACTIVE, LIQUID SUBSTANCE The invention relates to a device for evaporating an active, liquid substance, as set forth in the classification portion of claim 1 and to a process for producing this device. It is known from DE 37 37 272 Al a device of that class. In this device, a chemical, liquid, in particular an insecticide, is dragged up by the capillary action of a porous wick that is immersed in the chemical product, and is evaporated by a heating effect acting on the upper end of the liquid. the wick. In this device of the state of the art, the problem solved is that of improving the evaporation of the chemical product from a wick comprising an organic powder body. According to this solution, the inventor proposes to add an oxidation prevention agent to the mixture for the production of the wick, for which reason the purpose is to advantageously make it possible to avoid the obstruction of. the wick.

REF: 28091 However, in addition to the expense that is additionally required under the oxidation prevention agent, and in addition to the problem, which frequently occurs due to the leaky, porous wick, if the array is not stored in the vertical position, this device suffers from the disadvantage that the transporter or rate of evaporation of the insecticide (which is to say the amount per unit of time) varies to a very considerable degree depending on the filling condition of the container of the active substance; it has been found experimentally that the rate of evaporation when the container of the active substance is completely full differs considerably from that of a container that is almost empty. This inevitably causes the problem of an irregular and thus defective administration capacity of the insecticide. In addition, this confronts the designer of a suitable wick with the problem of sizing the wick so that, over the full fill height of the insecticide container, the evaporation rate provided is one that, on the one hand, accomplishes the desired purpose of destroying insects. while on the other hand, it limits the dosage administration of the insecticide to a level such that there is no possibility of harm to the health of the person who spends some time in the vicinity of the device; that problem is the one that weighs the most in that the usual insecticides such as for example those of the pyrethroid group are highly effective nerve poisons that can be basically dangerous to all living beings and with respect to which the threat is determined exclusively Due to the degree of dose administration, therefore, the precise administration of the dose is a fundamental requirement to effectively avoid any threat to health. Not minor due to the attitude of the public, which has become increasingly critical in recent times, in relation to insecticides based on evaporation in active, chemical substances, therefore, it is necessary, in terms of the future success of the market, provide evaporation devices with which it is possible to effectively combat the doubts and mistrust of that class. Therefore, the object of the present invention is to provide a device for evaporating an active, liquid substance, as set forth in the classification portion of claim 1, which allows more uniform evaporation of the active substance and which allows a speed of substantially constant evaporation in particular on the full, effective, filling height, from the lowest point in the submerged wick to the maximum level of the liquid. That object is achieved by the device for evaporating an active, liquid substance, as set forth in the classification portion in claim 1, by means of the characteristics of the characterization portion of claim 1. In this way, the configuration of the wick according to the invention prevents the liquid from penetrating the wick on its peripheral surface which is immersed in the active substance, liquid, and which is transported with the capillary flow in the direction towards the heating device. On the other hand, at any possible depth of immersion of the wick, the liquid can pass to the lowermost end of the wick in the region of the end surface that is placed at that point, and can provide a uniform flow in the wick . Advantageous developments and configurations of the invention are set forth in the appended claims and are described hereinafter. In this way, advantageously, the wick can be formed from porous, strong material, for example, a ceramic material, whereby mass production is particularly well suited as a mass-produced article and has reproducible properties. satisfactorily. A similar consideration applies with respect to the use of a lacquer or paint, a plastic material (for example, a plastic liner or cover) or an enamel (for example by means of powder coating) to achieve the desired property of the surface. peripheral. Preferably, the wick is substantially cylindrical. Advantageously, the wick is also provided with a coating in the region of the heating device, which provides in particular the advantage that, even if the device is not stored in a perpendicular position or if the device falls with the submerged wick, no the insecticide can emanate undesirably through the protruding portion of the wick. This is important in particular in terms of storage and transport of the device, until the moment it is first put into operation. In addition, advantageously, the coating, either only in the region of the heating device or long of the entire peripheral surface, may be such that the coating may be permeable for evaporation of the active substance in the region of the heating device. , only when the portion of the wick is heated to the operating temperature in that location; when the heating is effected, either the coating melts permanently in that region (dissolution at the time) or however, the coating is of a nature such that, upon being heated, it becomes permeable and then closes again when the The portion of the wick is subsequently cooled (reversible solution). It can also prevent the active, liquid substance from undesirably escaping from the portion of the wick to be heated. According to a preferred development of the invention, therefore, the coating may be such that, when the operating temperature of the range wick, in the region of the heating device, the coating melts or is destroyed from some other way and make the wick permeable for the evaporation of the active substance, in that region. In that development, which corresponds to the dissolution in a moment (see above), according to a further preferred configuration, the coating can be provided by sealing lacquer, wax or a material with comparable melting properties. On the other hand, according to a development of the invention, in the reversible dissolving manner (see above), the coating may be such that, when the temperature of operation of the stain is reached, in the region of the heating device, the coating becomes porous and thus permeable for evaporation and the active substance, while becoming impermeable at lower temperatures. In addition, it will be preferred that this coating be in the form of a rubber layer, rubber alone or comparable material. Finally, this coating can also advantageously be in the form of a membrane which is impermeable to the active substance, liquid, and permeable for the evaporation of the active substance. In an elegant manner, which on the one hand prevents the liquid from inadvertently passing to the peripheral surface, while on the other hand it provides the discharge of the evaporating active substance (evaporated) out of the portion of the heated wick without the liquid also be able to escape as a result. Preferably, the active, liquid substance is an insecticide or a perfume; other comparable substances are, however, also suitable for evaporation. Preferably, the heating device is incorporated using a PTC. Arrangement that not only provides the flexible and cheap use of electrical energy for the evaporation process, but at the same time the PTC, by virtue of its characteristic temperature-dependent resistance, also acts as a regulating element that always maintains the temperature of the heating device to a constant working point. Mechanically, the device according to the invention is preferably placed in a housing to which a container for the active substance is removably affixed, for example, for the purpose of replacement. According to a preferred development of the invention, the fixed between the container and the housing is particularly incorporated in a suitable manner by a screw connection. In a further preferred configuration, the housing can be easily equipped with a plug formed therein in a plug cavity so that it is supplied with electric current and at the same time mechanically maintained in its position. According to a further aspect of the invention, for which the protection is claimed independently, the wick which also, but not exclusively, is suitable for use in the device according to the invention, is produced by stretching or pressing (in particular, by extrusion) and subsequent calcination or ignition of a starting material that is prepared based on the ceramic base material. According to the invention, the ignition of the wick is carried out at an ignition temperature which is adjusted so that it is below the sintering temperature that is given for the stretching material. In this context the term sintering temperature is used to denote the temperature at which the stretching material, by virtue of the ignition, assumes a substantially pore-free, dense form, in which it is completely impermeable to the active, liquid substance. More specifically, according to the invention, it was found that the permeability of the stretch material (as the starting material for the wick) for the liquid is determined only by the ignition temperature; the higher the ignition temperature, correspondingly, the lower will be the evaporation rate of the wick that will be achieved with the wick, where virtually no additional liquid evaporates throughout the wick when the temperature is reached of sintering. In addition, the ignition time does not matter in this connection; the only important consideration is the maximum temperature reached, which is to say the temperature that is adjusted appropriately in the process according to the invention and thus controls the porosity of the wick. The advantages, features and additional details of the invention are apparent from the following description of the modalities by way of example with reference to the Figures, in which:Figure 1 is a schematic sectional view of the evaporation device according to a first embodiment. Figure 2 is a sectional view of a wick with a coating according to an additional embodiment. Figure 3 is a schematic, detail view of the heating device and the upper wick portion, according to still a further embodiment, and Figure 4 is a sectional view of a wick according to the state of the wick. technique. Figure 1 shows a first embodiment of the device for the evaporation of an active, liquid substance. This first embodiment will be interpreted in that respect as the best way to carry out the invention in effect. A container 1 in the form of a bottle of plastic material which is substantially cylindrical and tapering towards the opening and which is filled with the liquid insecticide is fixed in the region of its opening to a plastic housing 2 in such a way that it can be unscrew it. A heating device 3, schematically illustrated, is provided in the housing 2. For the generation of heat, the heating device 3 has a PTC resistance element 4, which is supplied with current by means of the main plug 5 which is equipped in accommodation. The main cap serves at the same time to mechanically retain the complete device in a plug cavity and is mounted rotatably in the housing 2 for adaptation to vertically or horizontally arranged contact pairs of this plug cavity, so that the device can always be maintained in a vertical position. Provided in the PTC element, for heat transmission, are the plates 6 which are made from die-cut portions and which are arranged to enclose a wick 7. On the one hand, the arrangement provides that the heat is transferred from the PTC to the wick over a distance as short as possible, and with the minimum level of losses, while on the other hand, the plates 6 forms adequately, which practically play free play, the wick, form a mechanical means to retain the wick 7 in the housing 2. Furthermore, since the ceramic wick 7 is not combustible, a device with a high level of operational safety can be achieved, in a manner such that, in contrast to for example a wick comprising coal or combustible material, comparable. In addition, since the ceramic wick 7 acts as an electrical insulator, the arrangement described is also operationally firm and electrically safe and can be produced without comprising an additional expense of electrical insulation. The wick 7 which is substantially cylindrical in the cross section comprises a porous clay body 8 which was produced by drawing or extruding and igniting a mixture comprising substantially clay and wood powder and mixed with water. According to a first embodiment, the wick 7 has, along its peripheral surface, a liner 9 extending from the lowermost end of the wick as shown in Figure 1 to the junction of the heating device 3. The peripheral surface in the region of the heating device 3 as well as the surfaces 10 and 11 of the lower and upper end of the wick remain free of the coating.

The coating 9 comprises a bale of acrylic lacquer or varnish (for example the commercially available nail varnish is also suitable). The wick 7 extends to the container 1 which is filled with a liquid insecticide 2 composed of a peritroid insecticide in a paraffin carrier liquid. It is ensured in this regard that the wicks are covered up to the maximum level of liquid filling in the container 1, on the peripheral surface of the wick, with the coating 9 which is impermeable for the liquid 12 and which is also insoluble in the liquid 12. In addition, a seal is provided that is not shown in the Figure, between the wick 7 and the container 1, in the neck thereof. In operation, the PTC heating element 4 is supplied with current by means of a main plug 5 and heated. The upper portion of the wick 7 which is placed in the region of the heating device 3 is heated by means of the plates 6 which act as a heat transfer medium. The liquid insecticide, which, by virtue of the capillary action within the wick 7, passes up to the wick 7 by means of the surface or face 10 of the lower end and passes upwards in the clay body 8 evaporates or vaporizes (these terms are used synonymously in the present application) by virtue of the heating effect in the region of the heating device 3 and is emitted from the wick in the gas form. In that case, the PTC heating element, depending on the requirements of the selected liquid insecticide, provides a substantially constant temperature in the usual range of between 100 ° to 140 ° C. The particular property of a PTC resistor, specifically that reacts to fluctuations in temperature with changes in resistance and thus produces an increase or fall in the current corresponding to the movements of temperature, is used in the present as a simple way to maintain the temperature in the upper portion of the wick, constant at a work point. By virtue of the coating 9 along the entire peripheral surface, which is immersed in the liquid insecticide, the continuous, subsequent flow of the insecticide can pass up to the clay body 8 which provides the transport effect, only in the region of the surface 10 of the lower end. That ensures that despite the filling height of the active substance, liquid 12 in the container 1, there is always a surface area, effective, equal, so that the continuous flow of insecticide passes through it, thus satisfying a prerequisite to give an evaporation rate that is constant over all fill heights. Reference will be made later in the present in Figure 4, which shows a porous, uncoated wick, which is known in the state of the art, to explain why the wick configuration according to the invention, in contrast to the known wick , allow a through flow of the liquid insecticide, which is substantially constant in all regions of the fill height. As shown in Figure 4 by means of the arrows, the active, liquid substance penetrates the porous wick through all submerged surfaces. Accordingly, a turbulence phenomenon 14 occurs inside the wick, in the main path of the conveyor (arrow 13) that extends vertically from bottom to top. The turbulence phenomenon 14 is in particular the result of secondary flows passing in the arrow in a transverse direction. The effects of turbulence 14 prevent the directed flow of the main conveyor and adversely influence the flow velocity and with this the evaporation rate. In addition, since less turbulence occurs with a falling level of liquid (due to liquid consumption), the influences on the flow of the main conveyor due to the effects of turbulence are also different, depending on the level of liquid. In comparison, by preventing the liquid from penetrating the wick in the transverse direction, in accordance with the present invention the disadvantageous effects, described above, are eliminated and it makes possible to have a liquid conveyor flow, appropriately directed, which is height dependent. of filling. In this regard, experiments have shown that the influence on the amount of distribution, due to the pressure that is dependent on the level of liquid, is significant. In the meantime, in the illustrated embodiment, a plastic lacquer or varnish was selected as the material for the coating 9, it can also be formed from any other material, for example, an enamel or a plastic liner or cover. The most important consideration is that the coating 9 is impermeable in relation to the liquid insecticide 12 and also can not be dissolved therein so that the coating 9 does not suffer from any disunion or dissolution, even in the case of storage for a prolonged period. of time. Preferably, the material adopted for the coating or varnishing of lacquer or varnish, is a material that does not per se penetrate deep into the porous clay body 8 in order not to obstruct the pores thereof and reduce in this way the area of the cross section, capillary action, effective. Figure 2 is a longitudinal sectional view through the wick 7 according to a traditional embodiment of the invention. In this embodiment, the liner 9 is thus placed in the clay body 8 covering the peripheral surface, complete with the clay body 8 and the surface 11 of the upper end. Figure 2 shows a wick in the condition as supplied and distributed, which can be equipped in that way in the arrangement shown in Figure 1 and that can be transported and stored together with the complete arrangement, without the liquid being capable of to escape from the upper end, even when the arrangement is in an inclined position. In this embodiment, the coating 9 is made from a material that, when heated, fuses locally in this manner, when first used in the evaporation device at the working temperature, cleans and opens the upper portion of the wick so that the gaseous insecticide emanates from it. Experiments have shown that, according to this embodiment, a material that has provided its value for the coating 9 is a thinly applied lacquer or sealing varnish whose melting temperature is somewhat below the working point of the coating. PTC or the evaporation temperature in the upper portion of the wick. However, it should also be possible to achieve a comparable result with another coating that is locally fused or destroyed in some other way, at the temperature in question and thus exposes the clay body of the wick in the region of the heating device . To act as a lid for the wick, which lid can be fused, it would also be possible to contemplate the use of a prestressed rubber cover, which could correspond approximately to an air balloon envelope, in terms of the material and the thickness comprised. The prestressed rubber changes its resistance with the increase in temperature. With proper sizing, it may then be possible to cause this cover to tear at the operating temperature and then be immediately exposed in the upper, complete evaporation region, due to the pre-tension effect. It will be appreciated that it is alternatively possible that the region be provided with a simple cover that can be adequately removed manually (or re-equipped again). Having considered the temperatures involved, for example, it is possible to use an active substance which, for the purpose of evaporation, requires a temperature in the region where the upper end surface of approximately 120 °, in which case the melting temperature or Destruction, preferably, of the local coating in that region could be adjusted to approximately 100 ° C. Figure 3 is a cross-sectional view of an upper portion of the wick according to still a further embodiment of the present invention. In this embodiment, the entire peripheral surface of the wick 7 and the surface 11 of the upper end are also covered with the coating 9. It will be noted that, in contrast to the second embodiment shown in Figure 2, the coating is maintained in all locations even during operation and is not partially distributed when the wick is heated for the first time. Thus, the gaseous insecticide can not be emitted, however, when heating occurs, the material adopted for the coating according to this embodiment must be a material that is permeable to the gaseous insecticide, at least in the heated condition. The rubber or natural rubber materials, which have the property of very large elongation and, when they are in the form of correspondingly thin layers, forming more or less thick pores, are suitable materials for a coating of this kind; when heated by the heating device, the material shrinks in a strut manner, and pores are formed in the coating, as shown in Figure 3, through which the gaseous insecticide can evaporate. The pores close again when the wick is subsequently cooled. Advantageously, this re-closing coating allows the hermetic transport of a device with filled insecticide container and equipped wick that has already been in operation. As an alternative, for the purpose of forming a coating that is permeable when heating occurs, it is possible to use a plastic material that is used for shrinkable tubes, known. As is known, shrinkable tubes of this kind have the property of contracting upon being heated and, as soon as the heating exceeds a period of time and / or temperature, pores or cracks or tears are formed in the material, so that the effect proposed in this way can be achieved. It will be appreciated, however, that in the shrinking operation, described, for the material of the shrink tube is in general irreversible, that is, the material does not close again when the wick is subsequently cooled. Alternatively, it is also possible to contemplate the use of membranes as the coating 9, which, (regardless of temperature) have openings through which the gaseous insecticide can pass in a recognized manner, but in contrast, the liquid insecticide can not . Membranes of that kind, for example, based on Teflon, are generally known and would need to be adapted appropriately to the size of the molecules and conditions that occur there. The embodiments described as being set forth purely by way of example in the present invention are not limited thereto. In this way, it is possible to contemplate in particular any desired wick shape and manner of manufacture and any desired cross section, while being carried out in effect and inventive principle, described. In particular, the term "periphery" in the present application is used to denote the peripheral surface of a wick of any shape or areas of the cross section. Thus, the concept of the present invention, in particular, also encompasses the feature that the coating on the peripheral surface, which is described by the reference numeral 9, for example, in Figure 1, does not extend completely downwardly. to the surface 10 of the lower end; on the contrary, the principle of the invention must be interpreted such that the coating 9 extends only over a large part of the peripheral surface that is immersed in the active substance, so that for example, a predetermined portion of the peripheral surface , which is smaller in relation to the surface of the coating, may still remain uncovered in the region of the end surface 10. The use of the present invention is also not limited to the evaporation of liquid insecticides. In this way, the device is also suitable in particular for the evaporation of liquid disinfectants, perfumes or comparable chemical products. Containers of a correspondingly suitable configuration will then be provided, in which with respect to the wick it is advantageously carried with its lower end surface (indicated at 10 in the Figure) in a lowermost room possible in this container, in order to allow the complete emptying of the same. In this way, in accordance with an advantageous development of the invention, it is possible in particular to promote the described distribution flow which is directed in the longitudinal direction of the wick, by virtue of the fact that the manufacture of the wick comprises the use of elongated wood fibers, cotton threads and the like, which are properly oriented already in the wick production material and which, then, in the finished wick, provide a pore arrangement, properly elongated. Since the present invention also comprises a product that is suitable as a mass-produced article, and that it should be possible to manufacture cheaply in large numbers, additional configurations that are suitable for this mass production are also judged to be particularly preferred. . They include, in particular, coatings on the wick that are produced by powder coating, lacquer varnish, varnish, winding, with brushes or paint brushes and / or when immersed in a suitable lacquer or varnish. A process for the production of a wick which is particularly suitable for use in an evaporation device of the kind described with reference to Figures 1 to 4 is described hereinafter.

A ceramic, cylindrical wick of this kind is produced, based on a cordierite material since it is usually employed as a carrier material for electric heating devices or the like. Materials of that kind are standardized for example by DIN VDE 0335. The described embodiment more accurately comprises a cordierite stretching material which, as substantial components, contains A1203 (approximately 34%), Si02 (approximately 49%) and MgO (approximately 2 %) . A stretching material of this kind has a pre-set ignition temperature (sintering temperature) of about 1300 ° C and after ignition at that temperature forms a completely sintered body, substantially impermeable to water, since it is required as an electrical insulator, highly resistant to heat, in its original area of use. Alternatively, it is possible to use a barium steatite stretching material containing BaO. The other manufacturing parameters that will be described later herein are the same. According to the invention, for use as a wick in the present case, the drawing material is thoroughly mixed in a manner recognized in the usual way with water (a ratio of about 10 to 20%) or drawing oil, and then The basic shape of the wick is determined by stretching and cutting to length; however, the ignition operation is carried out at a temperature that is markedly below the sintering temperature of 1300 ° C. For use according to the invention, it has been advantageously approved that the ignition temperature is adjusted to a range of between 1000 and 1200 ° C, preferably between 1050 and 1100 ° C, as far as it is concerned, it was found that the porosity of the the wick is dependent only on that established ignition temperature. The higher the ignition temperature is adjusted, the smaller the individual pores will become, and the lower the rate of transmission or evaporation of the active substance through the wick will be correspondingly lower. Therefore, in this regard, the ignition temperature controls the evaporation properties of the wick. It has been found further that the actual ignition period, which is usually about 12 hours, is without any influence on the porosity; the essential parameter, as mentioned, is the ignition temperature, established. It is to be noted in this connection that the wick according to this embodiment, with the exception of the drawing oil or water added to prepare the drawing material, should not contain any additional filler throughout (e.g. Similar) . The desired porosity is already given by virtue of the setting of the ignition temperature according to the present invention.

It is noted that in relation to this date, the best method known by the applicant to carry out the present invention is that which is clear from the present description of the invention.

Having described the invention as above, the content of the following is claimed as property:

Claims (12)

1. A device for evaporating an active substance, liquid, comprising: a wick that can be immersed in the active substance, liquid, to transport the active substance, wherein one end of the wick in the submerged condition protrudes from the active substance, liquid, and a heating device provided in the wick in the region of the projecting end, characterized in that: the wick is of a configuration such that on its peripheral surface it is substantially impermeable to the active substance, it liquids at least over most of its length that it is immersed in the active substance, liquid, is substantially permeable to the active substance, liquid in the region of its end surface which is opposite the projecting end, and is permeable to evaporate the active substance in the region of the heating device at least in the heated condition.

2. A device according to claim 1 characterized in that the wick comprises a porous, firm material,

3. A device according to claim 1 or claim 2, characterized in that on its peripheral, complete surface, with the exception of the region of the heating device, the wick is provided with a coating that is impermeable to the active substance, liquid, and that it is insoluble in the active substance, liquid.

4. A device according to claim 3, characterized in that the coating is produced by a lacquer coating, powder coating or by an enamel.

5. A device according to any of claims 1 to 4, characterized in that in the region of heating device, the wick is provided with a coating that is of such a nature that it becomes permeable for the evaporation of the active substance to a operating temperature of the wick, which is produced by the heating device.

6. A device according to claim 1 or claim 2, characterized in that on its peripheral surface, complete, the wick is provided with a coating that is impermeable to the active substance, liquid, and that is insoluble in the active substance, liquid, and which is such that it is permeable for the evaporation of the active substance, at an operating temperature of the wick that is produced by the heating device.

7. A device according to one of claims 1 to 6, characterized in that the heating device is in the form of a heating device, electric, with at least one PTC element, wherein the heat transfer from the PTC element to the wick occurs by means of an electrode of the PTC element, the electrode enclosing the wick in the region of the projecting end.

8. A device according to one of claims 1 to 7, characterized in that: the wick and the heating device are kept in a housing, a container for the active substance is provided, liquid, and the container is fixed removably to the container. accommodation .

9. A device according to claim 1, characterized in that a plug for inserting into a plug cavity and for retaining the device therein is provided in the housing.

10. A process for producing a device for evaporating an active, liquid substance, as set forth in claims 1 to 9, characterized by the following steps: preparing a pressing stretch material for the starting material, ceramic, - forming the wick to starting from the stretching or pressing material, adjusting a firing temperature for the wick to a temperature value which is below the sintering temperature of the stretching material, and igniting the wick at the set firing temperature.

11. A process according to claim 10, characterized in that the stretching material is a cordierite or a barium steatite stretching material and the firing temperature is adjusted to a value between 1000 and 1200 ° C.

12. A process according to claim 10 or claim 11, characterized by the following steps: providing the wick on its peripheral surface with a coating.